LISLE, ILL.— The Water Quality Association announced that the Wisconsin Department of Commerce formally has approved a system for sizing point-of-entry water-treatment devices such as softeners and filters that can be used as an alternative to current sizing requirements contained in the Wisconsin Uniform Plumbing Code.
The approval is based on data taken from a study commissioned by the WQA, “Analysis of Indoor Peak Demands in 60 Selected Single-Family Homes,” and conducted by Aquacraft Water Engineering & Management and an alternate sizing system application filed by the Wisconsin WQA.
According to a WQA spokesman, the study found that peak demand seldom exceeded 12 gpm, even in the largest houses. The Wisconsin plumbing code required sizing based on a fixture unit method that sometimes required filters to be sized to handle nearly 23 gpm.
The point-of-entry water-treatment device alternate sizing method is valid through August 2007. The Wisconsin Plumbing Code Council may consider in 2003-2004 amendments to the Wisconsin Plumbing Code to permanently include the alternate sizing method.
Language in the current Wisconsin Uniform Plumbing Code requires plumbers and installers to size POE water-treatment devices using traditional fixture unit value flow rate calculations. The code assigns a fixture unit value to plumbing fixtures such as baths, toilets, dishwashers, clothes washers and faucets, then converts the sum of the fixture unit values to a code design flow rate. That code design flow rate is then used to make sure that all fixtures will still operate after determining the difference between the incoming pressure and the pressure loss through plumbing pipes and devices such as water heaters, water meters and water-treatment devices.
When code design flow rates are too high, oversized POE water-treatment devices would be required by code. Oversized POE water-treatment devices operate inefficiently and are more expensive equipment for the consumer.
The home water-treatment industry has demonstrated that POE units operate efficiently between 7 and 10 gpm for sustained periods of time and can accommodate higher flows without sacrificing the quality of treated water.
The WQA/Aquacraft study analyzed indoor flow rates in 60 representative homes chosen by the Wisconsin Department of Commerce. The flows analyzed were from a two-week period in the summer and a two-week period in the winter. For the 60 homes contained in the study, the 90th percentile trend-line flow rate was 5 gpm or less and the 99th percentile trend-line flow rate was 7.1 gpm or less.
“Based on the results of this study it appears that indoor flows will almost never exceed 10 gpm,” explained Peter Boyer, Aquacraft project director.
“On the rare occasions they do exceed 10 gpm, these flow rates are typically sustained for only a few seconds.”
The Wisconsin Department of Commerce alternate approval applies statewide to sizing POE water-treatment devices installed in single-family homes or individual dwelling units in multifamily dwellings. If the water-treatment device provides treated water for exterior wall hydrants, flow rates for exterior wall hydrants are calculated using existing code criteria and then added to the alternate sizing method flow rate to size the POE water-treatment device. An example of the reduced design flow rates is shown in the table on pg. 7.
“The data in the study demonstrated that as the number of bathrooms increases in single-family homes that simultaneous use does not increase at the rate predicted by the current code,” said Loretta Trapp, program manager for Clack Corp., representing the Wisconsin WQA.
The national WQA will present flow rate data to national model plumbing code councils and interested states for guidance to plumbers and inspectors for possible inclusion in their respective codes.